Grinding disk segment for wood chips and the like



March 17, 1964 KQLLBERG ETAL 3,125,306

GRINDING DISK SEGMENT FOR WOOD CHIPS AND THE LIKE Filed May 25, 1962 3Sheets-Sheet 1 March 17, 1964 E. KOLLBERG ETAL 3,125,306

GRINDING DISK SEGMENT FOR WOOD CHIPS AND THE LIKE Filed May 25, 1962 3Sheets-Sheet 2 INVENTORS eve/c Jf'oLL8ERG- March 17, 1964 E. KOLLBERGETAL 3,125,306

GRINDING DISK SEGMENT FOR woon CHIPS AND THE LIKE Filed May 25, 1962 3Sheets-Sheet 3 United States Patent 3,125,306 GRINDING DISK SEGMENT FORWOOD CHIPS AND THE LIKE Eric Kollberg, Harrison, Emil Motla, Bronx, HansLarsen, White Plains, and Thor J ohansen, Nanuet, N.Y., assignors toAmerican Defibrator Inc., New York, N.Y., a corporation of New YorkFiled May 25, 1962, Ser. No. 197,744 1 Claim. (Cl. 241-298) Thisinvention relates to grinding disks of the character employed in anapparatus for grinding or defibrating wood chips or similar materials,and one of the objects of the invention is to provide a grinding surfacefor such disks which will materially improve the grinding operation.

Grinding disks as employed in defibrators are usually provided with aplurality of arcuately-shaped segments arranged end-to-end around theouter portion of the disks, and which segments are provided with ribbedgrinding faces. The chips to be ground are delivered to the center ofthe grinding disks where they are thrown outward by the centrifugalforce imparted to them by the vanes of the rotating segment holder. Theactual fiber separation takes place as the steam-softened chips passbetween the grinding segments. The fiber separation is materiallyaffected by the design of the grinding faces of the segments and thepresent invention relates to a new and improved grinding face for thesegments and by which improved results, with less wear on the grindingfaces, results.

At the present time, grinding segments as used, exhibit a tendency towear away faster adjacent to the periphery of the grinding disk due tothe high velocity, with inside concentrated metal wearing away moreslowly. As a result, a V-shaped opening develops from the outside of thesegments toward the inner portion, which results in poor defibration. Itis an object of the present invention to provide a grinding disk face inwhich the rapid wear, as above described, will be materially reduced.

It has also been noted that in grinding disks of known construction, andafter the segments thereof have been in operation for 500 to 600 hours,a concentric groove tends to develop in the segments on one of the diskswhile a corresponding ridge develops in the segments on the companiondisk. As a result, the passage of the material through the segments isslowed down and the useful life of the segments materially reduced. Itis an object of the invention to provide segments in which the aboveoccurrence is minimized; by which a more satisfactory grindingperformance is obtained and a more uniform type of fiber is secured andlonger life obtained for the segments with an improvement in powerconsumption.

More particularly, the invention contemplates the provision or anarcuately-shaped grinding segment having a plurality of spacedtransverse ribs on its operative face defining grooves between them andextending obliquely across the segment, said spaces or grooves beingbisected and interrupted at intervals by a plurality of cross ribsconstituting barriers or dams arranged in staggered relation.

With these and other objects to be hereinafter set forth in View, wehave devised the arrangement of parts to be described and moreparticularly pointed out in the claim appended hereto.

In the accompanying drawings, wherein an illustrative embodiment of theinvention is disclosed,

FIG. 1 is a face view of a grinding disk segment, constructed inaccordance with the invention;

FIG. 2 is an enlarged sectional view taken substantially on the line 22of FIG. 1, looking in the direction of the arrows;

FIG. 3 is a rear view of the segment;

FIG. 4 is a face view of another embodiment of the invention;

FIG. 5 is a sectional view, taken substantially on the line 5-5 of FIG.4, looking in the direction of the arrows;

FIG. 6 is a face view of another embodiment of the invention;

FIG. 7 is a sectional view, taken substantially on the line 77 of FIG.6, looking in the direction of the arrows, and

FIG. 8 is a sectional view, taken substantially on the line 88 of FIG.6, looking in the direction of the arrows.

In a defibrator or similar grinding apparatus, a pair offacially-opposed grinding disks are employed, one and sometimes both, ofsaid disks being rotated. The arcuate segments, three of which are shownin the accompanying drawings, provide the grinding surfaces on the disksand the same are mounted in end-to-end arrangement thereon to form theannular grinding face.

Referring to the drawings, and'more particularly to FIGS. 1 to 3inclusive, there is disclosed a grinding disk segment in the form of anarcuate plate or casting 1, the outer or peripheral edge of the samebeing indicated at 2 and its inner edge being shown at 3.

The grinding area of the disk segment is formed with a plurality ofrelatively closely spaced, obliquely extending ribs 4 having interveninglengthy grooves 5 between them. In the outer area of the segment, orthat area which extends inwardly from the periphery 2 for about one-halfthe width of the segment, the ribs 4 are of substantially uniform widthand depth, the grooves 5 between them being alike as to width and depth.The area above mentioned, and defined by the ribs 4 and the interveninggrooves 5 is the grinding area which reduces the wood chips or othermaterial to the required state of defibration.

Inwardly of the grinding area, as defined by the ribs and grooves abovementioned, the grooves widen and deepen, these wider and deeper partsbeing indicated at 6, so that inner portions 7 of the ribs 4 taper andincline at the top, as indicated at 8 in FIG. 2. The area in which thewidened grooves are located constitutes the feeding area.

Extending between and connecting the ribs 4 and directed tangentially tothe periphery of the segment is a plurality of cross ribs 10 which crossribs bisect and thus serve to interrupt the continuity of the transversegrooves 5 and form barriers or dams which extend angularly across thegrinding area. Each of these barriers or dams extends inwardly at anangle from the periphery of the segment and each has its inner end 11terminating at about the longitudinal center line of the grinding areaof the segment. It will be noted that in this embodiment of theinvention, the inner end 11 of each of the cross ribs 10 terminates at apoint on a line extending radially of the segment at which point thebeginning of the adjacent cross rib at the periphery of the segment islocated. As will be clearly seen in FIG. 1, the cross ribs 10 are instaggered and non-parallel relation to one another and the inner end ofeach of the cross ribs terminates below the outer end of the nextadjacent cross rib.

The segments 1 which, when placed end-to-end, form the grinding facesfor the disk, are secured to the disk in the known manner by means ofbolts extended through the holes 12 formed in bosses 13 seen on theunder side of the segment in FIG. 3.

When a grinding disk, composed of a plurality of the segments, is inrotative operation, the barriers or dams formed by the cross ribs 10,co-operate with similar ribs on the opposing disk to produce ascissoring action by which the grinding eifect produced on the materialis very substantially increased. These dams or barriers serve toPatented Mar. 17, 1964.

interrupt the radial flow of the material through the grooves 5 and theyforce the fibers of the material to be cut against the sides of the damsor barriers before the material can pass out through the grooves 5 inthe segments. The relatively deep and wide grooves 6 aid in producingthe desired grinding results, since the material to be ground entersbetween the disks at the center and it is initially rough or coarseground by the tapering, widely spaced ribs 7 and fed therefrom into theflat, finer-grooved grinding area where the grinding of the material tothe required degree takes place. By the use of segments constructed asabove described, a much finer fiber is secured, the passage of sliversand chips is eliminated and other advantageous results attained.

In the embodiment of the invention shown in FIGS. 4 and 5, the ribs 4extending transversely of the segment as described in connection withFIG. 1, are connected by cross ribs which are substantially similar tothe cross ribs 10, with the exception of the fact that each of the crossribs 15 extends on a curved line or arm tangentially from the peripheryof the segment and proceeds inwardly on such curved line to about thelongitudinal center of the grinding area or flat face of the segment.These cross ribs form dams or barriers and operate substantiallysimilarly to the cross ribs 10.

In the embodiment of FIGS. 4 and 5, the grooves 5, interrupted by thecross ribs 15, are not in end communication with the inner, widergrooves shown at 16. The rib portions 17 between which the wide grooves16 are located, are somewhat sharply tapered from the point 18 to theinner edge of the segment. Other ribs shown at 19 are provided Withrecesses 20 and as seen in FIG. 5, such ribs have considerably lesstaper.

It should be noted that the grooves 16 and 20 are so terminated thatthey form staggered dams or barriers which serve to eliminate theaccumulation of metal and the formation of ridges as explained inconnection with FIG. 1.

In the embodiment shown in FIGS. 6 to 8 inclusive, the ribs 4, with theintervening spaces 5, are interrupted by cross ribs which curve inwardlyfrom the periphery 2 of the segment toward the longitudinal center ofthe same. In this arrangement, the cross ribs 25 are not continuous butare regularly interrupted by intervening grooves. That is to say, thecross ribs present the aspect of curved broken lines extending along thelength of the segment. In operation this arrangement is substantiallysimilar to the embodiments previously described.

By means of the designs of the several segments, it has been foundpossible to materially increase the width of the grinding zone, therebykeeping the material longer in such zone and resulting in abetter-refined fiber. Also by the employment of barriers or dams in thesegments as herein described, the fiber cannot pass through the segmentsand leave the machine without being cut. In known types of segmentsthere is usually heavy metal concentrated at the point where the feedingand rough grinding meets the flat or finer grinding zone. Suchconcentration of metal often results in the formation of a high ridgeafter a few days of operation. As these segments tend to wear out fasterat their periphery due to the high velocity, the concentrated metalalways wears down at a slower rate than do the grooves in the grindingzone. As a result, a V-shaped opening appears from the periphery of thesegment to the above mentioned high ridge, which results in poorrefining. In the segments of the present invention, the designs are suchthat the higher ridge is eliminated so that the grinding zone will tendto remain constant.

Having thus described several embodiments of the invention, it isobvious that the same is not to be restricted thereto, but is broadenough to cover all structures coming within the scope of the annexedclaim.

What we claim is:

A grinding disk segment comprising an arcuate plate having an outer flatgrinding section which extends inwardly from the outer periphery of saidplate and merges with an inner dished feeding section which extendsoutwardly from the inner periphery of said plate, a plurality of spacedoblique transversely extending flaring grooves in said dished feedingsection which progressively increase in width from said fiat grindingsection to the inner periphery of said plate, said flaring groovescommunicating with aligned grooves of uniform width and depth in saidfiat grinding section which are of lesser depth and width than saidflaring grooves and extend outwardly from said flaring grooves to theouter periphery of said plate, and a plurality of spaced cross rib meanswhich extend angularly across said flat grinding section from the outerperiphery of said plate and terminate radially inwardly from the saidouter periphery with the inner end of each cross rib means beingdisposed in radial alignment with the outer end of the next succeedingcross rib means, each of said cross rib means intersecting a pluralityof said contiguous aligned grooves.

References Cited in the file of this patent UNITED STATES PATENTS1,026,818 McCulloch May 21, 1912 1,705,379 Sheppard Mar. 12, 19292,035,994 Sutherland Mar. 31, 1936 3,040,997 Borden June 26, 1962

